CComClassFactory implements the IClassFactory interface, which contains methods for creating an object of a particular CLSID, as well as locking the class factory in memory to allow new objects to be created more quickly. IClassFactory must be implemented for every class that you register in the system registry and to which you assign a CLSID.

ATL objects normally acquire a class factory by deriving from CComCoClass. This class includes the macro DECLARE_CLASSFACTORY, which declares CComClassFactory as the default class factory. To override this default, specify one of the DECLARE_CLASSFACTORYXXX macros in your class definition. For example, the DECLARE_CLASSFACTORY_EX macro uses the specified class for the class factory: